Discoloration inhibitors



United States Patent 3,330,766 DISCOLORATION INI HBITORS Seymore Goldwasser, Teaneck, N.J., assignor to Lever Brothers Company, New York, N.Y., a corporation of Maine No Drawing. Filed Oct. 20, 1965, Ser. No. 499,082 15 Claims. (Cl. 25299) This is a continuation-in-part of co-pending applica tion Ser. No. 322,536, filed Nov. 8, 1963, now abandoned.

This invention relates to the prevention of discoloration caused by the presence of manganese ions in washing solutions, and more particularly to cleansing and bleaching compositions suitable for use in manganese containing water.

It is a recognized problem in the detergent industry that manganese ions which are present in many water supplies cause severe staining of materials which are washed or cleaned in such water in the presence of bleaching agents. Such staining is commonly encountered in textile laundering and the cleaning of hard surfaced items, such as china, glassware, porcelain, plastics, silver, gold, and platinum.

Investigation has shown that the formation of yellow or brown stains on such surfaces is the result of the deposition of manganese dioxide which adheres to the surface. Strong bleaching agents which release chlorine or oxygen in solution oxidize the manganese ions in the water to a higher valence state and impart a yellowish stain to the object being cleaned. Detergent compositions which contain bleaching agents are now widely used in dishwashing machines and in clothes washing machines. When these detergent compositions are used in solutions which also contain manganese ions, objectionable stains are formed and soon become quite severe. Since the water supplies of many communities contain significant amounts of manganese, it is apparent that a serious problem exists.

It has been found that as little as 0.1 part per million of manganese ion in the water will cause objectionable stains on cloth within 5 to Washes when the cloth is I exposed to the manganese ion and a bleaching agent. As little as 1 to 3 parts per million of manganese ion in the water along with about parts per million of oxygen or about 200 parts per million of chlorine will severely discolor cloth in a single wash.

The need for protection against staining is particularly acute within the pH range generally encountered in cleansing and bleaching operations, that is from about 5.5 to about 10.5.

It is an object of this invention to prevent or inhibit the formation of stains caused by the simultaneous presence of manganese ions and a bleaching agent.

It is another object of this invention to inhibit the discoloration of textiles which are being washed in manganese containing wash water in the presence of a bleaching agent.

It is another object of the invention to prevent or inhibit the formation of manganese stains on hard surfaced items such as silverware, metal-decorated dinnerware, glassware, chain, porcelain and plastic objects when they are cleaned in a solution containing both a bleaching agent and manganese ions.

A further object of the invention is to provide staininhibiting compositions for use in manganese-containing solutions.

A still further object of the invention is to provide cleansing and bleaching compositions which are suitable for use in manganese containing water's.

It is also an object of the invention to provide a method for inhibiting the formation of manganese stains on both hard and soft surfaces which are being cleansed in a manganese-containing solution in the presence of a bleaching agent.

These and other related objects are achieved in accordance with this invention by incorporating, in a cleansing solution containing the stain-producing manganese ions, a stain inhibiting amount of a water soluble cerium compound. Accordingly, the presence of an effective amount of cerium ions in the solution which also contains manganese ions and a bleaching agent has been found to inhibit the formation of manganese stains on both textile surfaces and hard surfaces such as platinum, china, silver, glass and the like. The term cleansing solution, as used herein, refers to any solution employed to clean, wash 0r bleach either cloth or hard surface articles. Such cleansing solutions may contain detergents and bleaching agents or they may contain only bleaching agents.

A preferred stain inhibitor is a composition comprising both a water soluble compound capable of providing cerium ions in solution and a pyrophosphate salt such as an alkali metal pyrophosphate, e.g., sodium pyrophosphate, potassium pyrophosphate, and the like. In general, the small amount of pyrophosphate, e.g., about 5 percent or less, which is normally present in commercial tripolyphosphate, is sufficient to provide adequate protection. As little as about 1 weight percent of pyrophosphate in a detergent formulation or about 20-30 parts per million in the cleansing solution is effective to promote the stain inhibitingqualities of cerium ions.

The terms inhibiting amount and effective amount, as used herein, including the appended claims, refer to that amount of the inhibitor which is to be added to the manganese-containing cleansing solution in order to provide the desired degree of stain inhibition when used in accordance with the manufacturers directions, as for example, in a textile wash solution, a bleaching bath or a dishwashing solution.

Cerium ions for use in the practice of the instant invention may be provided by the use of water-soluble cerium compounds. Illustrative water-soluble cerium compounds include ceric nitrate, cerous acetate, cerous bromate, cerous bromide, cerous chloride, cerous nitrate, cerous sulfate, and the like or mixtures of rare earth salts containing cerium compounds. Cerium oxide, while normally considered to be insoluble in Water, has been found to be effective when added to a detergent composition and admixed therewith, e.g., in a soap crutcher, at an elevated temperature in the presence of polyphosphates and'a relatively high alkalinity (pH about 10), and accordingly is considered to be within the scope of the term water-soluble, which term is intended to describe any compound which is capable of providing the inhibitor concentration levels which are necessary for the prevention or diminution of manganese staining.

The herein disclosed inhibitors have been found to be effective in inhibiting manganese staining caused by manganese ions in the presence of bleaching agents capable of oxidizing manganese ions to a higher valence state such as halogen containing bleaching agents, e.g., potassium and sodium dichlorocyanurate, dichloroisocyanuric acid, trichlorocyanuric acid, dichlorodimethylhydantoin, N,N-dichloro-p-toluenesulfonamide, sodium chlorite, sodium and potassium hypochlorite and oxygen releasing bleaching agents, e.g., hydrogen peroxide, lauryl peroxide, potassium and ammonium monopersulfate, sodium perborate, sodium pyrophosphate peroxide and the like.

The actual amount of the inhibitor which is necessary to provide adequate protection depends on a number of conditions, e.g., the concentration of the manganese ions,

the concentration and nature of the bleaching agent, the

nature of the surface which is being cleaned, and the solubility of the cerium compound in the solution. The presence of detergent builders such as inorganic tripolyphosphates in the solution has been found to aid in the reduction of staining; accordingly, the presence of such builders may permit the use of lower concentrations of inhibitor.

The discoloration inhibitor can be added to or incorporated into the cleansing solution in a variety of ways. They may be formulated into dry or liquid detergent formulations, detergent-bleach formulations or bleach formulations for concurrent addition to the cleansing solution. For example, they may be conveniently admixed with synthetic detergent formulations containing one or more anionic or nonionic detergents in combination with inorganic builders such as condensed inorganic polyphosphates, e.g., tripolyphosphates and pyrophosphates. Alternatively, they may be packaged separately in liquid or dry form for selective addition to a Washing or bleaching bath. Since local water conditions vary and to a large extent determine the degree of staining, this procedure offers a more practical means of providing optimum inhibition under varying conditions.

In this connection, it is to be noted that many detergent formulas contain pyrophosphates as components thereof. In such cases it is only necessary to add the requisite amount of cerium compound to the detergent formula in order to obtain protection against manganese staining since such formulations generally contain commercial tripolyphosphates which contain sufficient pyrophosphate to promote the inhibiting action of the cerium ion.

Examples of detergents which may be present in the formulations in which the inhibitors of this invention are present include the well-known sulfated fatty alcohols, alkyl-substituted aromatic sulfonates, alkanesulfonates, hydroxyalkanesulfonate esters of aliphatic acids having about 10 to 18 carbon atoms, sulfonated fatty oils, sulfated and sulfonated alkoxy derivatives, sulfuric acid esters of monoglycerides, and taurine derivatives. The alkali metal, ammonium alkyl and alkanol substituted ammonium salts of these materials are ordinarily employed in the formulation of detergents. The inhibitors are also useful with nonionic detergents, such as ethoxylated alcohols, thioalcohols or acids; alkyl substituted phenols; alkylolamides of fatty acids; and nonionic detergents such as the pluronics which are polyoxypropylene polymers containing varying proportions of polyoxyethylene units in the molecule.

The detergent compositions can also contain builders, fillers, soil suspending agents and other conventional ingredients found in detergent formulations. The formulations may be prepared by conventional methods well known in the detergent industry such as by blending the ingredients in aqueous solutions or slurries and then spray drying at elevated temperatures.

In general, it has been found that at least about 0.5 part per million of cerium ions, and preferably at least about 2 parts per million of cerium ions, in the manganese ion-containing water will prevent the formation of stains on textile surfaces in the presence of from about 1 to 3 parts per million of manganese ions and about 200 parts per million of chlorine or about 15 parts per million of oxygen. Similarly, as little as about 5 parts per million of cerium ion in the cleansing solution will provide adequate protection against staining of hard surfaces. It will be apparent that the cost of the inhibitors herein disclosed will dictate that the minimum amount of inhibitor necessary to obtain satisfactory protection be used. In preparing textile detergent formulations for use in manganese ion-containing water, it has been found that about 0.2% by weight of a cerium compound in the detergent formulation provides a satisfactory degree of protection when the formulation is used in accordance with the manufacturers directions.

The following examples described the results obtained in a test laundry procedure employed to facilitate evaluation of the ability of the herein disclosed discoloration inhibitors to prevent manganese discoloration of textiles.

'4 Example 1 The following spray-dried anionic detergent compositions were prepared:

Composition, Percent by Weight Components Sodium phenyltetrapropylene-sulfonate 17. 15 17.15 17.15 Lauric isopropanolamide 3.00 3. 00 3. 00 Sodium tolnenesulfonate 2. 50 2. 50 2. 50 Sodium silicate solids (2.0 ra 6. O0 6. 00 6. 00 Tetrasodium pyr0phosphate 25.00 25. 00 25.00 Pentasodium tripolyphosphate 15.00 15.00 15.00 Water 7.00 7. 00 7. 00 Sodium carboxymethyleellulose 0. 30 0.30 0. 30 Sodium sulfate 21. 55 21. 24 21. 32 Misc. (dyes, perfumes, colorants, etc.) 2. 50 2. 50 2. 50 Cctous nitrate (=0.1% Ce) 0. 31 Cerium oxide (=0.1% Ce) 0.23

Swatches of white cloth were washed in a wash water containing about 0.1 part per million of manganese ions, 180 parts per million of calcium and magnesium ions in a ratio of about 2 to 1, about 0.25 weight percent of one of the detergent formulations described above, and about 200 parts per million of chlorine. The cloths were washed, under conditions which simulated normal laundry procedure, in a small washing machine with the temperature of the wash solution at about F. The wash procedure consisted of a Wash cycle and a fresh water rinse cycle, after which the cloths were squeeze dried. The cloths were Washed a total of 10 times using each of the described detergent formulations. Reflectance measurements were made on each sample after the second, fifth, and tenth wash, using a spectrophotometer at 430 millimicrons. The reflectance for each measurement on the various formulations are given below.

Composition Number Wash It is apparent that repeated exposure to wash water containing manganese ions and a bleaching agent has caused considerable loss of reflectance in the test performed with detergent compositions in which no inhibitor was employed, i.e., in compisition 1 above, whereas, the cloths washed with inhibitor-containing detergent formulations (composition 2 and 3) showed improved reflectance indicating substantial reduction of manganese staining after repeated washings.

Example 2 The following spray-dried nonionic detergent compositions were prepared:

1 Dodeoylphenol condensed with 10 moles (avg) of ethylene oxide.

2 Polyoxypropylenc havmg a molecular weight of from 1,500 to 1,800.

The washing procedure outlined in Example 1 was followed.

The reflectance measurements on these samples are given below:

It can be seen from the above data that the detergent containing the discoloration inhibitor, i.e., composition 2, is characterized by a significantly higher reflectance than composition 1, which is a control containing no cerium. This increased reflectance indicates the substantial reduction of manganese staining on the cloths washed with the inhibitor-containing detergents.

Example 3 A nonionic detergent formulation as described in Example 2, above, was divided into two portions. To one portion there was added 0.1 Weight percent cerium ion in the form of cerous nitrate. The second portion was used as a control and contained no inhibitor. Pieces of cotton cloth were washed in wash water containing 0.1 part per million of manganese ion using about 0.25 weight percent of each of the above formulations under identical conditions. The washing was conducted in two series. In one series about 200 parts per million of chlorine was added to the wash solution. In the second series no bleaching agent was used. The complete laundry cycle consisted of a fifteen minute wash period at about 120 F. followed by a three minute rinse. The laundry cycle was repeated times and reflectance measurements were made after the second, fifth, and tenth wash. The results are tabulated below:

Control 10.1% Wash No In- Cerium hibitor Ion 2 {Bleach 87. 5 88.1 No bleach... 87.5 87. 4 {Bleach 83.1 87.9 No bleach... 86.3 87.9 10 Bleach 65. 9 84. 9 No bleach 87. 4 86.4

This example illustrates the ability of cerium ions to prevent or diminish the discoloration of textile surfaces caused by the simultaneous presence of manganese ion and a bleaching agent.

Example 4 Four solutions as shown below, were prepared from water containing 3 parts per million (p.p.m.) of manganese ion and 200 parts per million of chlorine in the form of sodium hypochlorite:

(1) 1000 ppm. sodium tripolyphosphate;

(2) 1000 ppm. sodium tripolyphosphate and 30 ppm.

cerous nitrate;

(3) 1000 ppm. tetrasodium pyrophosphate;

(4) 1000 ppm. tetrasodium pyrophosphate and 30 p.p.rn.

cerous nitrate.

with a General Electric Recording Spectrophotometer at 430 millicrons.

Solution Number Cloth Type This example shows that discoloration occurs when manganese ions and bleach are present even in the absence of organic detergents and that cerium ion is effective as a manganese-stain inhibitor even in the absence of organic detergents.

In the following examples a test procedure has been developed to facilitate the study of discoloration inhibitors for hard surface materials. To accelerate discoloration, the manganese ion concentration employed in these tests is somewhat higher than the concentrations normally present in the water taken from average water supplies. The concentrations of detergent and chlorinating agents correspond to those normally used in conventional commercial formulas.

In the test procedure the sample to be tested was weighed into a marked 250 ml. Pyrex beaker, a platinum strip approximately 15 mm. x 15 mm. x 0.003 inch was suspended therein and about 200 m1. of Water containing manganese ion pre-heated to F. was added. The beaker containing the test solution and the platinum strip was then put into a water bath maintained at a temperature of about 143 F. After vigorous initial stirring to dissolve the sample, the test solution was agitated at frequent intervals. Several samples and a control were tested simultaneously and test solutions and platinum strips were observed closely for discoloration and other changes. Fifteen minutes after the addition of the water containing manganese ion, the platinum strips were removed from the solutions and examined. The strips were compared and graded against a control and were reintroduced into the solutions for an additional fifteen minute period. After a total exposure period of about thirty minutes, the platinum strips were again removed from the solution and examined, compared and graded. In certain cases, this procedure was varied to extend the total exposure period of the strips to more than thirty minutes.

Example 6 The following dishwashing formulation of a conventional type was used in the test described above:

Chlorinating agent to yield 0.9%1% available chlorine, based on total formula weight.

Sodium sulfate to make"--. 100.0

1 The following chlorina'ting agents were employed: potas sium dichlorocyanurate, dichloroisocyanuric acid, diehlorodimethylhydantoin, sodium chlorite, chlorine gas bubbled into solution, N,N-diohloro-ptoluenesulfonamide, sodium dichloroisocyanurate and trichloroisocyanuric acid.

The test solution consisted of 200 ml. of water containing 5 ppm. of Mn++ (143145 F.) and a sufiicient 4 amount of the above detergent to form a 0.25% solution. The resutls are tabulated below:

Percent inhibitor (basis dry formula Platinum discoloration after contact period of- No appreciable increase in discoloring after 1.5 hr. contact period.

When the detergent active in the above formula was replaced by sodium lauryl sulfate and lauryl hydroxyether sulfonate, the inhibiting effect of cerium salt and pyrophosphate remained unchanged.

Example 7 The above described tests were conducted with aqueous solutions containing ppm. Mn++ and cerium nitrate or cerium chloride. These inhibitors in levels below about 0.5% (based on dry formula weight) proved to be mildly effective in retarding platinum discoloring. Complete inhibition of discoloration during a minute contact period was effected at a cerium nitrate level of about 2%. This level however, did not completely prevent discoloration at contact periods greater than 15 minutes.

The above data show that the combination of a soluble pyrophosphate salt and a cerium compound is effective in retarding the discoloring of hard surfaces which come in contact with aqueous solutions containing manganese ion and halogenating agents. Since many detergent compositions contain pyrophosphates as active ingredients, it is evident that protection of hard surfaces from discoloration may readily be attained by the addition of a cerium compound to the detergent formula.

Various modifications and changes may be made in the compositions of this invention and in the manner of using such compositions, without departing from the spirit of the invention. Accordingly, it will be understood that the scope of the invention is to be limited only by the appended claims.

What is claimed is:

l. A detergent composition consisting essentially of an effective amount of a manganese stain inhibiting water soluble cerium compound and a synthetic nonsoap detergent.

2. A detergent composition consisting essentially of a synthetic non-soap detergent, an alkali metal pyrophosphate salt, and an effective amount of a manganese stain inhibiting water soluble cerium compound.

3. A detergent composition consisting essentially of a synthetic non-soap detergent, an alkali metal pyrophosphate salt, an effective amount of a manganese stain inhibiting water soluble cerium compound and a bleaching agent capable of oxidizing manganese.

4. A detergent composition consisting essentially of a synthetic non-soap detergent, a bleaching agent capable of oxidizing manganese and an effective amount of a manganese stain inhibiting water soluble cerium compound.

5. The composition of claim 3 wherein the bleaching agent is a halogen releasing bleaching agent.

6. The composition of claim 3 wherein the bleaching agent is an oxygen releasing bleaching agent.

7. A method of inhibiting surface discoloration caused by the presence in a solution of manganese ions and a bleaching agent capable of oxidizing manganese which comprises adding to the solution a discoloration inhibiting amount of water soluble cerium compound.

8. A method of inhibiting surface discoloration caused by the presence of manganese ions and a bleaching agent capable of oxidizing manganese in a cleansing solution which comprises adding to the solution effective amounts of a water soluble cerium compound and an alkali metal pyrophosphate.

9. A method of preventing the discoloration of textile surfaces in cleansing solutions containing manganese ions and a bleaching agent capable of oxidizing manganese which comprises the addition of at least about 0.5 part per million of cerium ion to the solution.

10. An aqueous washing and bleaching solution consisting essentially of a bleaching agent, a synthetic detergent, and at least about 0.5 part per million of cerium ion.

11. A method of inhibiting the discoloration of hard surfaces exposed to an aqueous solution containing manganese ions and a bleaching agent capable of oxidizing manganese which comprises adding a discoloration inhibiting amount of a material consisting essentially of an alkali metal pyrophosphate salt and a water soluble cerium compound to said solution.

12. The method of claim 11 wherein the hard surfaces are metallic.

13. A composition consisting essentially of an alkali metal pyrophosphate salt and a manganese stain inhibiting amount of at least one compound which furnishes cerium ion in aqueous solution, said composition being effective to inhibit discoloration of hard surfaces exposed to a soluton containing manganese ion and a bleaching agent capable of oxidizing manganese when said composition is added to said solution.

14. A method of inhibiting the discoloration of hard surfaces which occurs in solutions containing manganese ion and a. halogen containing bleaching agent capable of oxidizing manganese which comprises adding at least about 5 parts per million of cerium ion and from about 20 to about 30 parts per million of an alkali metal pyrophosphate salt to said solution.

15. A composition for use in preventing manganese staining of hard surfaces and textiles being Washed in a solution containing manganese ions and a bleaching agent capable of oxidizing the manganese ions, said composition consisting essentially of a water-soluble inert filler and an effective amount of at least one manganese stain inhibiting water-soluble cerium compound.

References Cited lated Material. Reinhold Pub. Co., N.Y., vol. 1 (1935), TP 9679, p. 163 relied on.

LEON D. ROSDOL, Primary Examiner.

ALBERT T. MEYERS, SAMUEL H. BLECH,

Examiners. M. WEINBLA'IT, Assistant Examiner. 

3. A DETERGENT COMPOSITION CONSISTING ESSENTIALLY OF A SYNTHETIC NON-SOAP DETERGENT, AN ALKALI METAL PYROPHOSPHATE SALT, AN EFFECTIVE AMOUNT OF A MANAGANESE STAIN INHIBITING WATER SOLUBLE CERIUM COMPOUND AND A BLEACHING AGENT CAPABLE OF OXIDIZING MANGANESE. 